Product Information

Description

Product details

Famciclovir is an antiviral medication used to treat herpesvirus infections in humans and cats. This product is a tablet formulation.

Used to control feline herpesvirus (FHV-1) in cats.
Helps to control (but not cure) herpesvirus infections, making symptoms less severe and more manageable.
Use with caution in animals with kidney impairment.
May be prescribed for other animal species; please consult your veterinarian.
While this drug does not have an FDA-approved indication for all animal uses, it is commonly accepted for veterinarians to prescribe this medication for use in animals.

*Please note: this is a generic medication. Product packaging and appearance, including size, color, and shape, may differ from the description or images provided and are subject to manufacturer availability.

Product sourced directly from the manufacturer or their approved distributor. Guaranteed genuine product backed by the manufacturer.

For

Cats

Active ingredient(s)

Famciclovir

Common brand names

Famvir

Drug class

Antiviral

Product strength & size

Famciclovir tablets may be available in multiple strengths and/or sizes. Please ensure the selected product and package size are appropriate for your pet, as recommended by your veterinarian.

For current availability, please refer to the product selection above.

Usage

Famciclovir Tablets should be given orally as directed by your veterinarian. Please consult your veterinarian before making any changes or discontinuing the prescribed dosing schedule.

This medication is typically recommended to be given on an empty stomach for best absorption (at least 1 hour before or 2 hours after feeding).

If your pet vomits or appears unwell after receiving a dose on an empty stomach, give future doses with food or a small treat. If vomiting continues, contact your veterinarian.

Missed doses

Administer the dose as soon as possible. If it is almost time for the next dose, skip the missed dose and continue with the regular schedule. Do not give two doses at once.

Storage

Store in a cool, dry place at a controlled room temperature (68 to 77°F, brief excursions permitted between 59 and 86°F). Keep in a tight, light-resistant container and out of the reach of children and pets. Store away from heat and direct sunlight. Do not store in the bathroom, near the kitchen sink, or in damp places. The medicine may break down if exposed to heat or moisture.

Side effects

This medication is generally well tolerated. Possible side effects include (but may not be limited to) diarrhea, vomiting, increased thirst and/or urination, decreased appetite, and excessive salivation.

Notify your veterinarian if your pet experiences any of the effects described above, or if you notice any other side effects that are persistent or troublesome.

If you notice anything unusual, please consult your veterinarian.

Precautions

Famciclovir should NOT be confused with acyclovir.

Use with caution in animals with kidney impairment; dose adjustments may be necessary in some patients.

Safe use of this medication has not been established in breeding, pregnant, or lactating animals. Discuss the risks of using this medication with your veterinarian if your pet is in one of these groups.

Do not administer to animals with a known history or suspected allergy/hypersensitivity to penciclovir, this medication (famciclovir), or any of its ingredients. Allergic reactions to medications may occur. Be sure to inform Vetsource and your veterinarian if your pet has any known drug sensitivities or allergies.

If your pet displays symptoms of an allergic reaction, discontinue therapy and call your veterinarian immediately or seek emergency veterinary attention. Symptoms may include (but are not limited to): swollen lips, tongue, face, or airways; difficulty breathing; agitation; profuse salivation; and widespread hives or itching.

Drug and food interactions

The following drugs* may have potential interactions with this medication: probenecid and spinosad.

*NOTE: this may not be a comprehensive list. Contact your veterinarian if your pet experiences any unusual reactions when different medications are given together.

Please ensure your veterinarian is aware of all medications and supplements that your pet is currently receiving. Your veterinarian may prescribe multiple medications, even if a potential drug interaction may occur. In these instances, your veterinarian may adjust the dosages or monitor your pet more closely.

Adverse reactions

If you are concerned that your pet has experienced an adverse reaction to this medication, please contact Vetsource Pet Owner Care at 877-738-4443.

Overdose

If you have any reason to suspect an overdose, call your doctor/veterinarian or the appropriate poison control resource immediately.

For humans:

The national toll-free Poison Help line, 1-800-222-1222, will connect you to your local poison center in case of emergency. This service is available nationwide and in most U.S. territories.

For animals:

The ASPCA Animal Poison Control Center is available 24 hours a day, 365 days a year at 888-426-4435.

Pet Poison Helpline® also provides a 24/7 animal poison control service at 855-764-7661.

*Please note: this information is for third-party services and is provided for convenience in case of potential poison-related emergencies. There may be consultation fee for these services.

Disclaimer

The content provided on this page is NOT medical advice.

All content, including the images and product description above, is intended for general informational purposes only and should not be considered a substitute for professional veterinary consultation, diagnosis, or treatment.

Consult your veterinarian for complete information about this product and how it fits into your pet's individual treatment plan.

Last revised: 6/25/2025

Description
Product details
Famciclovir is an antiviral medication used to treat herpesvirus infections in humans and cats. This product is a tablet formulation.
- Used to control feline herpesvirus (FHV-1) in cats.
- Helps to control (but not cure) herpesvirus infections, making symptoms less severe and more manageable.
- Use with caution in animals with kidney impairment.
- May be prescribed for other animal species; please consult your veterinarian.
- While this drug does not have an FDA-approved indication for all animal uses, it is commonly accepted for veterinarians to prescribe this medication for use in animals.
*Please note: this is a generic medication. Product packaging and appearance, including size, color, and shape, may differ from the description or images provided and are subject to manufacturer availability.

Product sourced directly from the manufacturer or their approved distributor. Guaranteed genuine product backed by the manufacturer.

For
Cats

Active ingredient(s)
Famciclovir

Common brand names
Famvir

Drug class
Antiviral

Product strength & size
Famciclovir tablets may be available in multiple strengths and/or sizes. Please ensure the selected product and package size are appropriate for your pet, as recommended by your veterinarian.
For current availability, please refer to the product selection above.

Usage
Famciclovir Tablets should be given orally as directed by your veterinarian. Please consult your veterinarian before making any changes or discontinuing the prescribed dosing schedule.

This medication is typically recommended to be given on an empty stomach for best absorption (at least 1 hour before or 2 hours after feeding).
If your pet vomits or appears unwell after receiving a dose on an empty stomach, give future doses with food or a small treat. If vomiting continues, contact your veterinarian.

Missed doses
Administer the dose as soon as possible. If it is almost time for the next dose, skip the missed dose and continue with the regular schedule. Do not give two doses at once.

Storage
Store in a cool, dry place at a controlled room temperature (68 to 77°F, brief excursions permitted between 59 and 86°F). Keep in a tight, light-resistant container and out of the reach of children and pets. Store away from heat and direct sunlight. Do not store in the bathroom, near the kitchen sink, or in damp places. The medicine may break down if exposed to heat or moisture.

Side effects
This medication is generally well tolerated. Possible side effects include (but may not be limited to) diarrhea, vomiting, increased thirst and/or urination, decreased appetite, and excessive salivation.

Notify your veterinarian if your pet experiences any of the effects described above, or if you notice any other side effects that are persistent or troublesome.
If you notice anything unusual, please consult your veterinarian.

Precautions
Famciclovir should NOT be confused with acyclovir.

Use with caution in animals with kidney impairment; dose adjustments may be necessary in some patients.
Safe use of this medication has not been established in breeding, pregnant, or lactating animals. Discuss the risks of using this medication with your veterinarian if your pet is in one of these groups.

Do not administer to animals with a known history or suspected allergy/hypersensitivity to penciclovir, this medication (famciclovir), or any of its ingredients. Allergic reactions to medications may occur. Be sure to inform Vetsource and your veterinarian if your pet has any known drug sensitivities or allergies.
If your pet displays symptoms of an allergic reaction, discontinue therapy and call your veterinarian immediately or seek emergency veterinary attention. Symptoms may include (but are not limited to): swollen lips, tongue, face, or airways; difficulty breathing; agitation; profuse salivation; and widespread hives or itching.

Drug and food interactions
The following drugs* may have potential interactions with this medication: probenecid and spinosad.
*NOTE: this may not be a comprehensive list. Contact your veterinarian if your pet experiences any unusual reactions when different medications are given together.

Please ensure your veterinarian is aware of all medications and supplements that your pet is currently receiving. Your veterinarian may prescribe multiple medications, even if a potential drug interaction may occur. In these instances, your veterinarian may adjust the dosages or monitor your pet more closely.

Adverse reactions
If you are concerned that your pet has experienced an adverse reaction to this medication, please contact Vetsource Pet Owner Care at 877-738-4443.

Overdose
If you have any reason to suspect an overdose, call your doctor/veterinarian or the appropriate poison control resource immediately.

For humans:
The national toll-free Poison Help line, 1-800-222-1222, will connect you to your local poison center in case of emergency. This service is available nationwide and in most U.S. territories.

For animals:
The ASPCA Animal Poison Control Center is available 24 hours a day, 365 days a year at 888-426-4435.
Pet Poison Helpline® also provides a 24/7 animal poison control service at 855-764-7661.

*Please note: this information is for third-party services and is provided for convenience in case of potential poison-related emergencies. There may be consultation fee for these services.

Disclaimer
The content provided on this page is NOT medical advice.
All content, including the images and product description above, is intended for general informational purposes only and should not be considered a substitute for professional veterinary consultation, diagnosis, or treatment.
Consult your veterinarian for complete information about this product and how it fits into your pet's individual treatment plan.

Last revised: 6/25/2025
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